Dental clutch fabrication

ABSTRACT

An improvement in the dental clutch fabrication means shown in U.S. Pat. No. 3,508,333 is described herein. The improvement permits use of but a single set of clutch support forks for endentulous and dentulous patients and provides preformed bearing pin guide means for greater precision of operation. The dental clutches, which are intaglio castings of the teeth, are formed on support forks that are secured in precise relationship to each other by jig means which has a separation plate to separate the clutches as they are formed. The clutches are preferably cast in the patient&#39;&#39;s mouth, directly on the teeth. The improved support forks described herein are combined with plates having bearing pin guide surfaces which have a preformed contour so that no difficulties are encountered in the forming of this guide surface. Two types of bearing surfaces are provided; a substantially flat planar surface for endentulous patients and a dished surface, preferably having a particular shape to encourage purely lateral and protrusive movements, for dentulous patients. The plates have means to index their position to the fork when casting the clutches and can be attached or unattached to the forks. The plates are preferably supported from the forks with attachment means which permits their removal so that they can be supplied in pairs and the undesired bearing surface can be removed from one of the forks which can then be used for forming the mandibular clutch, while the fork bearing the desired bearing surface is used for the maxillary clutch.

United States Patent [191 Guichet 451 Dec. 18, 1973 DENTAL CLUTCH FABRICATION Niles F. Guichet, 320 Olympia Place, Anaheim, Calif.

[22] Filed: Nov. 1, 1971 [2]] Appl. No.: 194,174

[76] Inventor:

Primary Examiner-Robert Peshock Attorney-Robert E. Strauss 57 ABSTRACT An improvement in the dental clutch fabrication means shown in U.S. Pat. No. 3,508,333 is described herein. The improvement permits use of but a single set of clutch support forks for endentulous and dentulous patients and provides preformed bearing pin guide means for greater precision of operation. The

dental clutches, which are intaglio castings of the teeth, are formed on support forks that are secured in precise relationship to each other by jig means which has a separation plate to separate the clutches as they are formed. The clutches are preferably cast in the patients mouth, directly on the teeth. The improved support forks described herein are combined with plates having bearing pin guide surfaces which have a preformed contour so that no difficulties are encountered in the forming of this guide surface. Two types of bearing surfaces are provided; a substantially flat planar surface for endentulous patients and a dished surface, preferably having a particular shape -to encourage purely lateral and protrusive movements, for dentulous patients. The plates have means to index their position to the fork when casting the clutches and can be attached or unattached to the forks. The plates are preferably supported from the forks with attachment means which permits their removal so that they can be supplied in pairs and the undesired bearing surface can be removed from one of the forks which can then be used for forming the mandibular clutch, while the fork bearing the desired bearing surface is used for the maxillary clutch.

17 Claims, 5 Drawing Figures PATENTEUUEEIBBIS Fl GURE Z FIGURE 5 FIGURE 5 INVENTO F. GUIC HET NILES ATTORNEY DENTAL CLUTCH FABRICATION DESCRIPTION OF THE INVENTION This invention relates to dental instruments and, in particular, to means for fabrication of dental clutches.

This invention comprises improvements in the forks and the clutches prepared therefrom that are described in my prior US. Pat. No. 3,408,333.

Dental clutches are castings which bear an intaglio pattern or impression of the teeth and which bear attachment means on their anterior surfaces to permit the attachment of dental instruments such as face bows, pantographs, etc. These clutches are useful to secure these instruments to the teeth. Prior to the intraoral fabrication disclosed in myaforesaid patent, the clutches were commonly formed by impressions taken from dental casts of the teeth. These were usually cast from aluminum and represented a considerable expenditure in the analysis of jaw movements with a pantograph.

In the aforementioned patent, the fabrication of clutches from a cold setting plastic such as an acrylic resin is described wherein upper and lower support forks are secured to ajig, the forks are covered with the resin and the assembly is placed in the patients mouth. The patient is then instructed to bite into the plastic and the impressions of the teeth are made in the resin masses which surround the forks. The jig serves to align, precisely, the two support forks to each other and to the patients teeth. The jig also supports a separation plate, typically formed of soft rubber, which separates the upper and lower forks and prevents the resin from cementing the forks together. The rubber plate removably supports, on its under surface and at about the center of the forks, a bearing pin with its lower end projecting into the resin about the lower fork. This pin becomes embedded in the resin and is thereby cemented to the lower fork. The upper surface of the separation plate, at a location above the bearing pin, has a raised surface with a predetermined contour which imparts a bearing surface for the end of the bearing pin in the underside of the upper clutch. This bearing surface is preferably contoured to direct the bearing pin along purely lateral and protrusive movements when the clutches are mounted in the patients mouth, thereby greatly improving the operation of a pantograph attached to the clutches.

The aforedescribed clutch fabrication means was quite a departure from prior devices and methods for dental clutch fabrication and has been used successfully for several years. This successful use, however, has revealed a few disadvantages which, although minor in nature, have prevented achievement of the high degree of efficiency of which the fabrication means and method are capable.

In particular, the fabrication means does not have provision for the intra-oral casting of clutches of endentulous or partially endentulous patients and a separate device has been necessary for preparation of clutches from these patients. This duplication of devices which function similarly but are of substantially different structure would represent an unnecessary investment in equipment if a universally adaptable fabrication means were available.

In some instances, it has also been observed that irregularities can be formed in the bearing surface molded in the underside of the upper clutch; these are formed by air bubbles in the acrylic resin which can be eliminated by thorough mixing of the resin before use. The necessary degree of mixing, however, is often not achieved in the press of time in dental laboratories.

It is therefore an object of this invention to provide means for the fabrication of dental clutches which can be used for edentulous and/or dentulous patients.

It is also an object of this invention to provide clutch support forks which are adaptable to either edentulous or dentulous patients.

It is a further object 'of this invention to provide such means that are also useful in the intra-oral casting of Y clutches.

It is an additional object of this invention to provide precontoured bearing surfaces which become an integral portion of the dental clutches.

It is a still further object of this invention to provide means in the clutches which serve as limiting stops or curbs to the excursions of the mandible.

Other and related objects will be apparent from the following description of the invention.

The aforestated objects are secured by my invention which comprises a generally flat plate which provides the bearing or guiding surface to the bearing pin means. The plate is combined with a clutch support fork and bears index means which align and position the plate between the sidearms of the fork. Preferably, the pates are secured to the fork by attachment means which permits removal of the plate. The plate can be substantially flat, and thereby present a bearing surface to the clutch separation or bearing pin which is suitable for edentulous or partially edentulous patients or it can have a dished surface and thereby present a bearing surface to the clutch separation pin which is suitable for dentulous patients. Preferably, the forks and dependent plates are combined in pairs with one of each of said plates being supplied in combination with a clutch fork. The user can select the fork and a plate having the desired bearing surface and use the remaining fork without a plate for casting the lower clutch.

The clutch forks have an open, generally U-shape with a bight and dependent sidearms for positioning adjacent the outside buccal surfaces of a patients teeth. The sidearms lie in acornmon plane and the bight bears means for the removable attachment of the forks to dental instruments and indexing means to orient the fork to such instruments in a precise manner.

The flat plate can be secured to the fork by means such as tongue means which can be integral with the fork and which projects from the rear face of the bight to support and index, i.e., align the plate in a central position between the dependent sidearms and in or substantially parallel to the common plane of the sidearms. If the plate is supplied separate from the fork or the tongue is to be removed before use, the plate also bears index means. The tongue has a fracture line permitting the removal of the plate from the fork when desired. The plate, preferably, has a rim about its extremities to present a curb or limiting stop to the bearing pin and thereby serve to limit mandibular movements within the bearing surface area of the platesThe clutch forming jig and its separation plate are similar to those described in my prior patent except, however, the separation plate does not bear an intaglio pattern of the bearing surface for the upper or maxillary clutch. Preferably, the plate carries a groove to mate with the rim of the plate on the support fork to permit seating of the rim in the plate when the clutches are cast.

The invention will now be described with reference to the FIGURES, of which:

FIGS. 1 and 2 illustrate a pair of support forks of the invention;

FIG. 3 illustrates the clutch forming jig and separation plate used with such forks;

FIG. 4 illustrates a support fork with the bearing plate removed therefrom and thus suitable for the casting of the lower or mandibular clutch; and

FIG. 5 illustrates the attachment means and indexing means carried on the anterior face of the bight of the support forks.

Referring now to FIG. 1, one of the pair of support forks which comprise the preferred combination of the invention is shown. The fork 12 has a generally U- shape with a bight 12a and dependent sidearms 12b lying in or along a common plane which is shown by the broken lines. Preferably, the arms spread outwardly at about 30 to 60 total included angle to approximate a typical angle of a dental arch. The sidearms are shown as being polygon in cross section with inner chamfered edges to provide a slightly raised rib 12c which extends along the inside faces of the sidearms 12b and bight 12a. This shape is preferred for maximum strength and lightness, however, it is not critical and other cross sections for the arms can be provided. The arms are also preferably tappered to a minimal cross sectional area at their free ends as shown. The bight has a flat anterior face 13 that is generally perpendicular to the plane and that carries index means such as key 16 which engages a track on the jig described hereinafter.

A substantially flat plate is attached to the clutch support fork by tongue means 14 which projects from 'the rear surface of the bight to index or align the plate in its correct position, substantially in the central area between the sidearms 12!). Preferably, plate 15 is removably attached to the support fork and this is attained by providing tongue means 14 with one or more scores 17 and 18 which weaken the material of the tongue means 14 and thereby provide a fracture line across tongue means 14. A row of apertures or other means which weaken the material could also be used for this purpose.

In the most preferred embodiment, the undersides of the plates 15 and 19 are provided with one or more, preferably several, recesses 50 which are positioned at predetermined positions therein. The recesses could extend through the plate, however, it is preferred that they terminate within the plate to avoid difficulties with the curing plastic when the clutches are cast. The recesses cooperate with bosses such as 51 which are shown on plate 32 of FIG. 3 and the combination serves as indexing means to achieve exact alignment of the plate when the clutches are formed. This construction permits the complete detachment of plates 15 or 19 from their support fork prior to use and elimination of tongue 14. The tongue extends between the incisal teeth and thus prevents complete closing of the jaw. Since the maximum precision in operation of most dental instruments can not be readily achieved when the teeth are separated to any marked degree, it is preferred to minimize the degree of separation of the teeth. The most preferred construction achieves this by providing index means 50 and 51 and means permitting the complete removal of the tongue prior to use; e.g.,

second fracture line 18. Even though the tongue 14 is not used as index means during casting of the clutches in this most preferred embodiment, it can still be useful in retaining the plate and fork in combination during manufacturing and handling of these members.

The plates could also be supplied as items separate from the support forks when they bear independent index means such as. recesses 50 and cooperative bosses 51 are present on plate 32. The tongue means 14 would, therefore, be absent in this construction.

The clutch support forks can be fabricated from various materials having a high strength to weight ratio, e.g., aluminum, magnesium, or preferably plastics such as Nylon, Teflon, Delrin, etc. Preferably a plastic which does not take a permanent set such as a thermoplastic material having a relatively low deformation temperature is used such as XT Polymer, an acrylic polymer marketed by American Cyanamide. Other thermoplastics which are capable of being slightly deformed by hand pressure at ambient temperatures or slightly above ambient temperatures can be used so that the free ends of the forks can be hand formed to accomodate a variety of dental arches simply by spreading or closing the included angle between these sidearms.

The plate 15 and tongue means 14 can be formed of the same material as the fork and are, preferably, integral with the fork in a single casting or molding.

While the embodiment of plate 15 shown in FIG. 1 is flat and thereby suitable for use with edentulous patients, that of FIG. 2 has a dished surface 20. The fork and the tongue means are similar to that of FIG. I, however, this FIGURE illustrates the tongue with only one fracture line 17 and without recesses 50. The tongue serves as the index means and this plate would be used with a plate such as 32 which, however, does' not have bosses 51.

The plate 19 can have a conventional dished bearing surface, e.g., one having a spherical contour, however, it is preferred to employ the illustrated shape which discourages protrusive movement of a patients jaw during lateral excursion. This insures the proper jaw movements when the clutches are secured to gnathological instruments. The proper shape is achieved by a depression 20 in the anterior central region of the plate; The depression which is viewed from its opposite side in FIG. 2 is formed with a raised track 39 which lies along the longitudinal axis of the fork with an inclination to the plate at its anterior end of between about 3 and 15, preferably about 7, and an inclination along its posterior end of between 20 and 35 to the plate. Preferably, the inclination at the posterior end is about 24.

At the posterior of this track is disposed the lateral tracks 40 and 41 in the form of a V with its apex pointed posteriorly. The wings of this V-shaped track extend laterally and slightly anteriorly. The flat areas 45 and 44 contiguous to these tracks present irritations that restrain the patient from making a mandibular excursion in the direction of these areas. Instead, the pa tient is directed or encouraged in a purely protrusive movement along track 39 or lateral excursion along tracks 40 or 41. While the upper surface of depression 20 is molded to conform to the contour of the under surface, such construction is not essential and this upper surface could have any convenient shape that would insure that it would not provide undue obstruction in the mouth and that it would readily cement to the clutch as it is cast in the mouth.

FIG. 3 illustrates a clutch forming jig 22 which comprises a plate 25 with a support arm 26 extending from its rear face. The opposite face of plate 25 has the aforementioned means to mate with the index means carried by each fork. These comprise tracks 29 and 30 which are at predetermined positions relative to each other to orient the upper and lower forks into the proper vertical separation. The tracks also have apertures 23 which extend into plate 25 to provide seats for bosses that are carried on the rear faces of the keys 16 of the forks. The tracks and apertures and the mating keys and bosses of the forks together comprise the means for orienting, precisely, the forks to each other when the clutches are cast so that the forks are retained in a predetermined vertical, lateral, longitudinal and angular relationship to each other.

In casting of clutches with the forks and jig illustrated in FIGS. l-3, both clutches are simultaneously cast and it is therefore necessary to impose a separation plate between the upper and lower clutches to prevent the plastic used in forming these clutches from bonding together. Such a separation plate is illustrated as 32 and comprises a generally flat plate formedofa soft flexible rubber or similar material. This plate has a tongue 33 which extends into a recession 34 on. the face of plate 25. The tongue can be notched on its underside at 26 to provide an index to indicate the degree of retraction of the tongue in the recession 34.

The clutch separation plate 32 also serves to hold the center bearing or clutch separation pin 35 in the proper position for casting this pin in the lower clutch. This is accomplished by means, e.g., hole 36 in the under surface of the plate 25 which is positioned at about the center of the plate and beneath the dished surface 20 when the fork of FIG. 2 is indexed and attached to jig 22. A generally semi-circular wall 37 is supported at the rear central edge of plate 32; this wall serves to retain the plastic casting resin about the forks during casting of the clutches and thereby insure that the teeth become properly embedded in the plastic without extrusion of the plastic away from the teeth. Plate 32 can also bear, on its upper surface, one or more boses 51 to mate with recesses and index the plates to the forks, thereby eliminating the tongue means 14.

In the preferred embodiment, the under surface of the flat bearing plates bear, along their peripherial edge, a rim such as 43 which is shown in FIG. 2. Preferably, both the flat plate 15 shown in FIG. 1 and plate 19 are provided with this rim. The rim serves to limit the jaw excursions during use of the clutches by providing a curb or obstruction means to the end of the bearing pin and thereby serves to retain the bearing pin beneath the plates. The rim can extend about the entire edge of the plate or can be provided only along the lateral sides of the plate. Preferably, the rim extends about the entire edge of the plate.

Referring now to FIG. 3, the separation plate, preferably, has a groove 38 which has the same shape as rim 43 and thereby provides a seat in which this rim can be fitted. This serves to retain the plates 25 and 19 in proper orientation, but more importantly, minimizes the vertical separation of the clutches during their fabrication.

FIG. 4 illustrates a clutch support fork which has the central bearing plate, either 15 or 19, removed. This fork is useful for the casting of the lower or mandibular clutch and is secured in the lower track 30 of jig 22 with its flat planar surface 11 contiguous to the undersurface of plate 25. Also shown in this F IG. 4 is the central bearing or clutch separation pin 35 which is fitted into the hole 36 previously described. The head of this pin is set in hole 36 and the threaded lower end projects beneath plate 25 and becomes embedded in the plastic used in forming the mandibular clutch. When the clutch is removed from the jig 22, pin 35 is also removed from hole 36. This pin can be rotated in the clutch to advance or retract the pin and thereby permit variation in the vertical spacing between the clutches. The head of the pin, of course, bears against the bearing surfaces of plates 15 or 19 which are cast in the maxillary clutch.

FIG. 5 illustrates the anterior surface of the bight of a support fork. This surface has one or more bosses 18 which project from the face of the key means 16 which are also carried on the anterior face of the bight. The bosses are bored and threaded at 24 to provide means for their removable attachment to dental instruments as well as to jig 22.

While the invention has been described with reference to the illustrated and preferred embodiments, it is not intended that such illustration be unduly limiting of the invention. Instead, it is intended that the invention be defined by the means and their obvious equivalents set forth in the following claims.

I claim:

1. A clutch support fork adapted for support of dental impressions and having an open, generally U-shape with a bight and dependent sidearms for positioning adjacent the outside buccal surfaces of a patients teeth, said sidearms lying in acommon plane, said bight having attachment means to permit the removable attachment of said fork to dental instruments with means to index said fork thereto; a substantially flat plate member carried by said fork in a central position between said sidearms and substantially parallel to said plane, and rim means about at least the lateral extremities of the undersurface of said plate member.

2. The fork of claim 1 wherein said plate is carried by said fork with attachment means to removably secure said plate to the rear face of the bight of said fork.

3. The fork of claim 2 wherein said attachment means is tongue means extending from said rear face of the bight of said fork to said plate and wherein said tongue means has at least one transverse fracture line to permit its easy removal from said fork.

4. The fork of claim 1 wherein said fork is formed of plastic material permitting spreading or closing of said sidearms to accomodate varied widths of dental arches.

5. The fork of claim 1 in combination with a support jig bearing means for the removable attachment of at least one of said forks thereto, a clutchseparation plate comprising a flat member having slightly greater outer dimensions than said fork and means securing said separation plate to said support jig subjacently to said fork.

6. The combination of claim 5 including means for removable attachment of a second fork subjacently to said separation plate.

7. The combination of claim 15 including recesses carried on one of the under surface of said plate member and upper surface of .said clutch separation plate and mating bosses therefor carried by the other of said surfaces.

8. The fork of claim 1 wherein said plate is a smooth flat plate. I

9. The fork of claim 1 wherein said plate has a central, indented surface concavely oriented towards the said common plane. I

10. The Combination of two of the forks as defined in claim 3 wherein one of said forks bears'a smooth flat plate and the other of said forks bears a plate having a central, dished surface.

11. The fork of claim 9 wherein said central, indented surface has a contour that encourages purely lateral and protrusive jaw excursions.

12. The fork of claim 1 wherein said rim means extends about the lateral and anterior extremities of the undersurface of said plate.

13. The combination of claim wherein said clutch separation plate bears groove means for seating of said rim means.

14. The combination of a clutch support fork adapted for support of dental impressions and having an open, generally U-shape with a bight and dependent sidearms for positioning adjacent the outside buccal surfaces of a patients teeth, said sidearms lying in a common plane, said bight having attachment means to permit the removable attachment of said fork to dental instruments with means to index said fork thereto, a support jig with said fork secured thereto by said attachment means, a clutch separation plate comprising a flat member having slightly greater outer dimensions than said fork, means securing said separation plate to said support jig subjacently to said fork, and a substantially flat plate member carried by said separation plate in a central position between said sidearms and substantially parallel to said plane.

. 15. The combination of claim 14 wherein said plate bears rim means about at least the lateral extremities of its under surface.

16 The combination of claim 14 wherein said plate bears rim meansabout the lateral and anterior extremities of its under surface.

17. The combination of claim 14 wherein said clutch separation plate bears groove means for seating of said rim means. 

1. A clutch support fork adapted for support of dental impressions and having an open, generally U-shape with a bight and dependent sidearms for positioning adjacent the outside buccal surfaces of a patient''s teeth, said sidearms lying in a common plane, said bight having attachment means to permit the removable attachment of said fork to dental instruments with means to index said fork thereto; a substantially flat plate member carried by said fork in a central position between said sidearms and substantially parallel to said plane, and rim means about at least the lateral extremities of the undersurface of said plate member.
 2. The fork of claim 1 wherein said plate is carried by said fork with attachment means to removably secure said plate to the rear face of the bight of said fork.
 3. The fork of claim 2 wherein said attachment means is tongue means extending from said rear face of the bight of said fork to said plate and wherein said tongue means has at least one transverse fracture line to permit its easy removal from said fork.
 4. The fork of claim 1 wherein said fork is formed of plastic material permitting spreading or closing of said sidearms to accomodate varied widths of dental arches.
 5. The fork of claim 1 in combination with a support jig bearing means for the removable attachment of at least one of said forks thereto, a clutch separation plate comprising a flat member having slightly greater outer dimensions than said fork and means securing said separation plate to said support jig subjacently to said fork.
 6. The combination of claim 5 including means for removable attachment of a second fork subjacently to said separation plate.
 7. The combination of claim 15 including recesses carried on one of the under surface of said plate member and upper surface of said clutch separation plate and mating bosses therefor carried by the other of said surfaces.
 8. The fork of claim 1 wherein said plate is a smooth flat plate.
 9. The fork of claim 1 wherein said plate has a central, indented surface concavely oriented towards the said common plane.
 10. The combination of two of the forks as defined in claim 3 wherein one of said forks bears a smooth flat plate and the other of said forks bears a plate having a central, dished surface.
 11. The fork of claim 9 wherein said central, indented surface has a contour that encourages purely lateral and protrusive jaw excursions.
 12. The fork of claim 1 wherein said rim means extends about the lateral and anterior extremities of the undersurface of said plate.
 13. The combination of claim 5 wherein said clutch separation plate bears groove means for seating of said rim means.
 14. The combination of a clutch support fork adapted for support of dental impressions and having an open, generally U-shape with a bight and dependent sidearms for positioning adjacent the outside buccal surfaces of a patient''s teeth, said sidearms lying in a common plane, said bight having attachment means to permit the removable attachment of said fork to dental instruments with means to index said fork thereto, a support jig with said fork secured thereto by said attachment meaNs, a clutch separation plate comprising a flat member having slightly greater outer dimensions than said fork, means securing said separation plate to said support jig subjacently to said fork, and a substantially flat plate member carried by said separation plate in a central position between said sidearms and substantially parallel to said plane.
 15. The combination of claim 14 wherein said plate bears rim means about at least the lateral extremities of its under surface.
 16. The combination of claim 14 wherein said plate bears rim means about the lateral and anterior extremities of its under surface.
 17. The combination of claim 14 wherein said clutch separation plate bears groove means for seating of said rim means. 